truss rod length

i noted that cheap ebay rods are considerably shorter that those from the stewmac, allied luthier etc.

so how does the length of the truss rods affect their function? i would guess that the longer would be the better.

is there a general rule of thumb to determine optimum rod's length?

thanks

Are you talking single action or double action?

Sorry. I was talking double action.

But love to hear yr opinion in both instances.

I only use single action truss rods so someone else can better talk about double action rods.

A single action rod will probably have to be cut and threaded to fit a specific neck application.

I only use single action truss rods so someone else can better talk about double action rods.

A single action rod will probably have to be cut and threaded to fit a specific neck application.

Ya - on single action rods I just cut them so that I have .2" to .25" of thread to put the adjusting nut on - pretty simple on those. Never used a double-action rod.

Thanks for the replies,seems pretty straight forward. I think even more so on heel adj necks.

On nut adjusted necks,i see that the anchors positions vary quite a bit. Aside from replicating the original design,any specific considerations?

In general, you're right, the longer, the better. It's true for traditionally-built accoustics, and set-necks too, that the truss rod shouldn't extend into the heel of the neck. You don't want to be forcing mechanical movement into or around a glued joint. I've seen it argued that it's the same for bolt on necks too. Of course, too long is bad, too, unless you consider truss rod sticking out over your peghead, or over the neck pickup a decorative feature.

The two-way rods I've gotten from an ebay seller (Bitterrootguitars) come in different lengths. 17" total length seems to work well for the builds I do now, and I think will fit the shorter-scale necks I plan to build someday.

BTW, if you haven't seen JWells thread on this forum about how he does single-action truss rods, start to finish, do yourself a favor and check it out. I think most people around here consider it the definitive tutorial on the subject. There are variations possible, of course, but Jack's method is well explained, clearly illustrated, and effective. I think Jack's 2010 Challenge build thread has it.

thanks for the reply. the rod i see at ebay is a bit short of 17" so these might still be ok for tele.